The discredited stem cells known as STAP cells were ultraflexible because they were really embryonic stem cells, a new report contends.

Last January, researchers claimed in two papers published in Nature that they had made stem cells by briefly dipping adult cells in a dilute acid bath or by giving the cells a squeeze (SN: 2/22/14, p. 6). The research was soon called into question, and an investigation by RIKEN, the Japanese research institute where much of the work was done, found lead author Haruko Obokata guilty of manipulating images and plagiarizing parts of the text. The papers were retracted in July (SN: 7/26/14, p. 7).

After months of failing to replicate her work, Obokata resigned and RIKEN said it would cease efforts to re-create the cells.

On December 26, RIKEN issued a report saying that what the researchers claimed were STAP cells were really embryonic stem cells contaminating the lab dishes. The contamination probably wasn’t accidental, but exactly who was responsible for it could not be determined. The investigators found Obokata guilty of two more counts of misconduct for fabricating data.

The report may close the book on a year-long saga that has marred stem cell science (SN: 12/27/14, p. 25).